Liquid-cooled rotary electric machine integrated with an inverter

ABSTRACT

A rotary electric machine includes a rotor for rotation around a rotational axis, a stator core that has a cylindrical shape and includes a slot therein, a cooling unit having a coolant passage, and a casing that accommodates the rotor and the stator core. A stator coil is inserted in the slot of the stator core and has a coil end protruded from a side face of the stator core. An electric part is mounted on the cooling unit and controls a current of the stator core. The rotor is rotatably supported inside of the stator core. The cooling unit cools both the stator core and the electric part. The cooling portion is accommodated in spacing defined by the side face of the stator core and an outer circumference wall of the coil end.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application relates to and incorporates herein by referenceJapanese Patent Applications No. 2002-73030 filed on Mar. 15, 2002, No.2002-192429 filed on Jul. 1, 2002, No. 2002-192430 filed on Jul. 1,2002, and No. 2002-300888 filed on Oct. 15, 2002.

FIELD OF THE INVENTION

[0002] The present invention relates to a liquid-cooled rotary electricmachine integrated with an inverter.

BACKGROUND OF THE INVENTION

[0003] Recently, many rotary electric machines for an automotive vehicleare proposed. For example, Japanese Patent No. A-05-292703 proposes aliquid-cooled rotary electric machine integrated with an inverter, whichcools both an inverter and a motor with a coolant. In this rotaryelectric machine, the inverter is fixed on the sidewall of the motorthrough a heat sink, and includes a semiconductor switching device and asmoothing capacitor. The heat sink cools both the motor and theinverter. However, the smoothing capacitor is big so that a large areais needed to attach the smoothing capacitor. Thus, a principal plane ofthe heat sink, where the smoothing capacitor is attached, necessarilybecomes large. In addition, the semiconductor switching device generatesa large amount of heat, so that the device needs to be cooledsufficiently. Therefore, the rotary electric machine has to be improvedfor a smaller size, lighter weight, and higher cooling performance.

SUMMARY OF THE INVENTION

[0004] The present invention has objects to reduce size and weight andto promote a cooling performance of a rotary electric machine, moreparticularly, the cooling performance for cooling both an electric partand a motor.

[0005] In the present invention, a rotary electric machine includes arotor, a stator core, a stator coil, a casing, a cooling unit, and anelectric part. The rotor is rotatably supported inside of the statorcore so that the rotor rotates around a rotational axis of the rotaryelectric machine. The stator core has a cylindrical shape and includes aslot therein. The stator coil is inserted in the slot of the statorcore, and has a coil end protruded from a side face of the stator core.The casing accommodates the rotor and the stator core. The electric partis mounted on the cooling unit and controls a current of the statorcore. The cooling unit includes a coolant passage so that the coolingunit cools both the stator core and the electric part. The cooling unitis accommodated in spacing defined by the side face of the stator coreand an outer circumference wall of the coil end.

[0006] Although the above spacing is normally a redundant space, thespacing is used as an accommodation space for the cooling uniteffectively. Therefore, the rotary electric machine becomes compact.Further, the cooling unit can be compact, so that the rotary electricmachine reduces weight. Moreover, the cooling unit contacts both thestator core and the electric part, so that the cooling performance forcooling both the electric part and the stator core can be promoted.Furthermore, the coil end of the stator coil and the electric part aredisposed closely, so that a wiring resistance loss and anelectromagnetic radiation noise can be reduced.

[0007] Preferably, the rotor, the stator core, the stator coil, and thelike form an alternating current motor. More preferably, the electricpart forms an inverter unit. The inverter unit is disposed on an axialend of the motor, and controls electric power delivery between anexternal direct current power supply and the stator coil of the motor.Here, the inverter unit includes a semiconductor switching device, asmoothing capacitor, and a cooling unit. The cooling unit has first andsecond surfaces, where the first surface faces the motor, and the secondsurface is opposite to the first surface.

[0008] The semiconductor switching device is disposed between theexternal direct current power supply and the stator coil, and forms aninverter circuit for converting direct current to alternating current oralternating current to direct current. The semiconductor switchingdevice is mounted on the first surface of the cooling unit so that thesemiconductor switching device is cooled by the cooling unit. Thesmoothing capacitor connects to a direct current terminal of theinverter circuit, and is mounted on the second surface of the coolingunit so that the smoothing capacitor is cooled by the cooling unit.

[0009] In the above inverter unit, both surfaces are used as principalplanes for cooling both the semiconductor switching device and thesmoothing capacitor, so that the rotary electric machine with theinverter can be downsized and lightened. Moreover, the semiconductorswitching device does not face the motor, so that the semiconductorswitching device is cooled sufficiently.

[0010] More preferably, the inverter unit includes first, second, andthird busbars, first and second electric parts. Here the first andsecond electric parts forms the above inverter circuit. The first busbaris mounted on the surface of the cooling unit through an insulationsheet. The first electric part is mounted on the first busbar. Thesecond busbar includes a body mounted on the surface of the cooling unitthrough the insulation sheet and a leg protruded from the body. Thesecond electric part is mounted on the body of the second busbar. Thethird busbar is mounted on the surface of the cooling unit. A bottomface of the leg of the second busbar is connected to a top face of thefirst electric part, and the second busbar has a predetermined stepbetween the body and the leg of the second busbar. A bottom face of thethird busbar is connected to a top face of the second electric part.

[0011] In this case, a heat generated by the first electric partconducts the first and second busbars through the top and bottom facesof the first electric part, so that the first semiconductor device iscooled sufficiently by the cooling unit through the first and secondbusbars. Similarly, the second electric part is also cooled sufficientlyby the cooling unit through the second and third busbars.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

[0013]FIG. 1 is a schematic partially cross-sectional view showing arotary electric machine according to a first embodiment of the presentinvention;

[0014]FIG. 2 is a partially enlarged cross-sectional view showing therotary electric machine shown in FIG. 1;

[0015]FIG. 3 is a partially enlarged cross-sectional view showing arotary electric machine according to a modification of the firstembodiment;

[0016]FIG. 4 is a circuit diagram showing a control unit for a rotaryelectric machine according to a second embodiment of the presentinvention;

[0017]FIG. 5 is a partially cross-sectional view showing the rotaryelectric machine according to the second embodiment;

[0018]FIG. 6 is a partially cross-sectional view showing a rotaryelectric machine according to a third embodiment of the presentinvention;

[0019]FIG. 7 is a partially enlarged cross-sectional view showing therotary electric machine shown in FIG. 6;

[0020]FIG. 8 is a rear view showing a rotary electric machine accordingto a fourth embodiment of the present invention;

[0021]FIG. 9 is a partially enlarged cross-sectional view showing therotary electric machine taken along line IX-IX in FIG. 8;

[0022]FIG. 10 is a rear view showing a rotary electric machine accordingto a modification of the fourth embodiment; and

[0023]FIG. 11 is a partially enlarged cross-sectional view showing arotary electric machine according to further modification of the fourthembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] (First Embodiment)

[0025] A rotary electric machine according to a first embodiment isshown in FIG. 1. This rotary electric machine is a brushless three-phaseDC motor, however, any other type of motor can be used as a rotaryelectric machine. The rotary electric machine includes a front frame 1having a ring shape, an rear frame 2 having a ring shape, an rear plate3 having a ring plate shape, a stator core 4, a stator coil 5, a rotor6, a rotational shaft 7, a cooling fan 8, a through bolt 9, asemiconductor switching device 10, and a cover 11. A front plate (notshown), the front frame 1, the rear frame 2, and the rear plate 3 areformed by aluminum die-casting method. The front plate has almost thesame structure as the rear plate 3 does, and the front frame 1 has thesame structure as the rear frame 2 does. The front plate connects to thefront frame 1, similar to a connection between the rear plate 3 and therear frame 2.

[0026] Each collar 12 a, 12 b is protruded from each radial outside endof the rear frame 2 and the rear plate 3, respectively. Each collar 12a, 12 b has a through hole (not shown). Similarly, other collars (notshown) are protruded from the radial outside ends of the front frame 1and the front plate. The other collars have also through holes (notshown). A through bolt 9 is installed through each through hole of thecollars 12 a, 12 b, respectively. The front plate, the front frame 1,the rear frame 2, the stator core 4, and the rear plate 3 are assembledin this order, and are bolted by the through bolt 9 with a nut.

[0027] A bearing 13 is disposed on the inside end of the rear plate 3,another bearing (not shown) is also disposed on the inside end of thefront plate. These bearings 13 support the rotational shaft 7 rotatably.The rotor 6 is fixed and interlocked to the rotational shaft 7, andfaces the stator core 4 with a gap for electromagnetic field.

[0028] The stator coil 5 is interlocked in a slot 14, which is formed onan inner circumference wall of the stator core 4. The rear end of thestator coil 5 in the axial direction is protruded from the stator core4, so that a coil end 15 of the stator coil 5 is formed. The cooling fan8 is fixed to the rear end of the rotor 6. In this embodiment, thecooling fan 8 is a centrifugal fan.

[0029] An electronic control unit for controlling a current of thestator coil 5 is fixed to the rear side of the rear plate 3. The controlunit includes the semiconductor switching device 10 having a three-phaseinverter circuit. The cover 11 has a ring plate shape with a collarhead, and is fixed to the rear side of the rear plate 3 so that thecover 11 covers the control unit.

[0030] A connector 16 is fixed to the rear side of the rear plate 3, andis protruded from the rear plate 3 through the cover 11. The connector16 connects to a DC power supply cable 17 and to a signal cable (notshown). The rotary electric machine communicates an external system withthe signal cable. The DC power supply cable 17 supplies an electricpower to the control unit through the connector 16, a busbar 42, and thelike.

[0031] A cooling system of the front side of the rotary electric machineis almost the same as a cooling system of the rear side of the rotaryelectric machine. Therefore, the cooling system of the rear side of therotary electric machine is described as follows. As shown in FIG. 1, abody 21 and a cylinder 22 form the rear side of the rear frame 2. Thebody 21 has a cylindrical shape, and is accommodated in a space that isdefined by the stator core 4, the coil end 15, and the rear plate 3. Thecylinder 22 has a cylindrical shape, and is protruded from the body 21to the front side. A coolant passage 23 is formed in the body 21, and isa helical passage. The coolant passage 23, for example, is formed withquadruplet. The coolant passage 23 has openings on the rear side of thebody 21. The coolant passage 23 connects to another coolant passage 31through the openings. The front side of the body 21 has no opening ofthe coolant passage 23. The coolant passage 31 is formed in the rearplate 3, and is a helical passage. The rear side of the rear plate 3 hasno opening of the coolant passage 31.

[0032] One end of the coolant passage 31 connects to a coolant inletpipe 32, and the other end the coolant passage 31 connects to a coolantoutlet pipe 33. Both the coolant inlet and outlet pipes 32, 33 areconnected to an external pump (not shown), so that coolant is circulatedby the external pump. Liquid or gas coolant can be used as the coolant.An O-ring 34 is disposed in a ring groove of the rear plate 3, andprevents the coolant from leaking.

[0033] The body 21 is crimped to the rear side of the stator core 4 bythe through bolt 9 and the nut. The inner circumference wall of thecylinder 22 contacts the outer circumference wall of the stator core 4with thermo-conduct grease. Therefore, the stator core 4 is cooled withthe coolant circulating the coolant passages 23, 31. A space having ateacup shape is formed between the body 21 and the coil end 15.

[0034] The cooling fan 8 raises a blow. The blow blows to the coil end15 and the body 21 through the space, and is cooled with the coolant. Acooling fin 24 is formed on the inner circumference wall of the body 21,and cools the blow sufficiently. Then, the blow blows along the frontside of the rear plate 3 and is also cooled by a cooling fin 35 of therear plate 3. After that, the blow comes back to the cooling fan 8. Thisflow of the blow is indicated by arrow in FIG. 1.

[0035] The coolant cools the rear plate 3, which is also used as a heatsink of the semiconductor switching device 10. Therefore, thesemiconductor switching device 10 mounted on the rear side of the rearplate 3 is cooled with the coolant sufficiently. The coolant preventsthe bearing 13 from over-heating.

[0036] A wiring of the stator coil 5 is as a three-phase lead 50 shownin FIG. 2. A through hole (not shown) for retrieving the three-phaselead 50 is formed in the rear plate 3. A ferrite core 36 is mounted inthe through hole of the rear plate 3. The ferrite core 36 has a C-shapewith a notch. A printed circuit board 37 is fixed to the rear side ofthe rear plate 3. An electric part 38 as a control circuit is mounted onthe printed circuit board 37. A current detector 40 built in a Hallelement 39 is fixed to the front side of the printed circuit board 37,and is inserted in the notch of the ferrite core 36. As shown in FIG. 1,the three-phase lead 50 of the stator coil 5 is connected to an ACoutput terminal of the semiconductor switching device 10 with busbar 42through the ferrite core 36 and the printed circuit board 37.

[0037] The body 21 as a cooling unit is accommodated in a space, whichis defined by the rear frame 2, the rear plate 3, the stator core 4, andthe coil end 15 of the stator coil 5. This space is normally a uselessspace. Therefore, the rotary electric machine according to the firstembodiment becomes compact, compared with the related art. Further, thecooling unit can be compact, so that the rotary electric machine reducesweight. Moreover, the cooling unit, i.e., the body 21, contacts thestator core 4, so that the stator core 4 and the stator coil 5 mountedin the stator core 4 are cooled sufficiently by the cooling unit.Furthermore, the coil end 15 and the semiconductor switching device 10are disposed closely, so that a wiring resistance loss and anelectromagnetic radiation noise are reduced.

[0038] The first embodiment is modified as follows. As shown in FIG. 3,the rear frame 2 and the rear plate 3 are integrated to be a rear frame100. The rear frame 100 has a cylindrical shape with a bottom. A ringgroove 102 is formed outside of the rear frame 100, and a coolant pipe103 is disposed in the ring groove 102. A coolant flows in the coolantpipe 103.

[0039] Further, although the through bolt 9 bolts the parts of therotary electric machine, it is preferred that two bolts are used insteadof the through bolt 9. In this modification, the first bolt with a nutbolts the front plate and the front frame 1, the second bolt with a nutbolts the rear plate 3 and the rear frame 2. Even when the first bolt isunfastened, the coolant does not leak from the coolant passage 23, 31.

[0040] Further, a space between the coil end 15 and the body 21 may befilled with a good heat conductive material such as a resin mold. Inthis case, the cooling performance of the stator coil 15 will be morepromoted.

[0041] (Second embodiment)

[0042] A rotary electric machine according to a second embodiment has anelectric circuit configuration shown in FIG. 4. The electric circuitincludes a battery 201, a motor 202, and an inverter unit 203 as acontrol unit. The motor 202 is a three-phase synchronous motor, and theinverter unit 203 converts direct current (i.e., DC) to alternatingcurrent (i.e., AC) or AC to DC between the battery 201 and the motor202, so that electric power is delivered between the battery 201 and themotor 202, i.e., the inverter unit 203 is used as a regeneration unit.

[0043] The inverter unit 203 includes a three-phase inverter circuit210, a smoothing capacitor 211, a current detector 212, and a gatecontroller 213. The three-phase inverter circuit 210 includessemiconductor switching devices 204-209, which includes metal-oxidesemiconductor transistor (i.e., MOS transistor). The gate controller 213as a micro-computer control device outputs an information signal of theinverter unit 203 to an external control system 214, receives a torqueinformation command from the external control system 214, and calculatesa current data detected by the current detector 212, so that the gatecontroller 213 controls the motor 202 with a duty control of thethree-phase inverter circuit 210.

[0044] The smoothing capacitor 211 absorbs a voltage change generated byon/off control of the semiconductor switching devices 204-209, so thatan electric potential change on DC lines 215, 216 is suppressed. Thus,deterioration of the battery 201 and an electromagnetic radiation noiseare reduced. A line 217 connects a positive terminal of the smoothingcapacitor 211 to the higher potential DC line 215. A line 218 connects anegative terminal of the smoothing capacitor 211 to the lower potentialDC line 216.

[0045] As shown in FIG. 5, the motor 202 includes a stator core 221, astator coil 222, a rotor 223 having a permanent magnet, and a rotationalshaft 224. The stator coil 222 is inserted in the stator core 221, andincludes a coil end 225. The stator core 221 is fixed to a housing (notshown). The rotor 223 is interlocked and fixed to the rotational shaft224. The rotational shaft 224 is rotatably supported with the housing.

[0046] A heat sink 230 is a main component of the inverter unit 203, andis used as a cooling unit. The heat sink 230 is fixed to the housing,and has a square plate shape. A coolant passage 231 is disposed in theheat sink 230. More particularly, the coolant passage 231 is disposedfrom almost center to outside in the radial direction of the heat sink230, but is not disposed on the inside of the heat sink 230. The heatsink 230 faces the coil end 225 of the stator coil 222 with apredetermined spacing therebetween, and has front and rear faces 232,233 as principal planes. A smoothing capacitor 211 and a currentdetector 212 are disposed on the front face 232. The smoothing capacitor211 is adjacent to the coolant passage 231. The current detector 212includes a ferrite core 321 having a C-shape with a notch and a Hallelement 322 accommodated in the notch of the ferrite core 321. Athree-phase lead 331 is installed through a center hole of the ferritecore 321, and is protruded from the coil end 225 of the stator coil 222in the axial direction. The three-phase lead 331 is also installedthrough the heat sink 230, and is protruded from the rear face 233 ofthe heat sink 230. Semiconductor switching devices 204-209 forming athree-phase inverter circuit 210, a gate controller 213, and conductivewires for connecting the devices 204-209 to the gate controller 213 aredisposed on the rear face 233 of the heat sink 230.

[0047] The semiconductor switching devices 204-209 are adjacent to thecoolant passage 231. A DC line 215 as a conductive wire is mounted on athin insulating sheet on the rear face 233 of the heat sink 230, and hasa higher electric potential. A DC line 216 as a conductive wire ismounted directly on the rear face 233 of the heat sink 230, and has alower electric potential. The DC line 216 can be also mounted on a thininsulating sheet on the rear face 233. Three-phase lead of thethree-phase inverter circuit 210 is mounted on a thin insulating sheeton the rear face 233 of the heat sink 230. The three-phase lead includesthree leads, and, for example, one of them is a U-phase lead 219. Thethree-phase lead is formed of flat copper wire.

[0048] The semiconductor switching devices 205, 207, 209 are disposed onthe inside of the rear face 233 of the heat sink 230, and connect to anAC line. The semiconductor switching devices 204, 206, 208 are disposedon the outside of the rear face 233 of the heat sink 230, and connect tothe DC line 215. The three-phase lead 331 of the stator coil 322includes three leads and connects to the three-phase lead of thethree-phase inverter circuit 210, respectively, for example, to theU-phase lead 219. The connection between the three-phase lead 331 of thestator coil 322 and the above three-phase lead of the three-phaseinverter circuit 210 is covered with a resin member 220.

[0049] A line 215′ connects a lower potential electrode of thesemiconductor switching device 204 and the DC line 215. A line 219′connects a lower potential electrode of the semiconductor switchingdevice 205 and the DC line 216. The DC line 215 connects to a higherpotential electrode of the smoothing capacitor 211 through a line 217.The DC line 216 connects to a lower potential electrode of the smoothingcapacitor 211 through a line 218.

[0050] The gate controller 213 is mounted on the DC line 216, but isinsulated to the DC line 216. The gate controller 213 receives adetection signal from the Hall element 322 through a line 323 that isinsulated to the heat sink 230. Then, the gate controller 213 applies acontrolling voltage to each gate electrode of the semiconductorswitching devices 204-209 through each line (not shown).

[0051] In the second embodiment, the front and rear faces 232, 233 ofthe heat sink 230 are used as principal planes for cooling both thesemiconductor switching devices 204-209 and the smoothing capacitor 211,so that the heat sink 230 is downsized. Moreover, a total length of therotary electric machine in the axial direction is substantiallyshortened, compared with a double-layer type rotary electric machine, inwhich the semiconductor switching devices are mounted on the heat sinkand the smoothing capacitor is mounted on the semiconductor switchingdevices on the heat sink. Moreover, the cooling performance of thesemiconductor switching devices 204-209 promotes more than a case thatthe smoothing capacitor 211 is mounted on the rear face 233 and thesemiconductor switching devices 204-209 are mounted on the front face232, which is opposite to the second embodiment. That is, because thesemiconductor switching devices 204-209 need to be cooled more thanother electric parts. If not, the semiconductor switching devices204-209 are much affected by a heat generated by the motor 202 and thenthe semiconductor switching devices 204-209 are heated and operatedfaulty.

[0052] The heat sink 230 can have any shape, as long as the heat sink230 has a pair of principal planes extending in the radial direction.Moreover, air cooling system or liquid cooling system can be used as thecooling unit. Although the motor 202 in the second embodiment has theabove structure, other types of AC motor can be used.

[0053] (Third Embodiment)

[0054] A rotary electric machine according to a third embodiment isshown in FIGS. 6 and 7. This rotary electric machine has acharacteristics that a coolant passage 231 has openings on a front face232′of the heat sink 230, and a flat surface 310 of a smoothingcapacitor 211 adheres to the front face 232′ so that the openings of thecoolant passage 231 are closed by the flat surface 310 of the smoothingcapacitor 211.

[0055] In detail, the smoothing capacitor 211 is a film capacitor, andincludes a dielectric film and an electrode assembly 312 in FIG. 7,which is a pair of electrodes sandwiching the dielectric film. Theelectrode assembly 312 is accommodated in a resin casing 311. A rearface of the resin casing 311 forms the flat surface 310 of the smoothingcapacitor 211, and is adhered to the coolant passage 231. The heat sink230 having the coolant passage 231 is formed by aluminum die castingmethod, for example.

[0056] Although a bonding between the flat surface 310 of the smoothingcapacitor 211 and the front face 232′ of the heat sink 230 is performedby resin bonding method, another bonding method can be used. Forexample, a metal film is deposited on the flat surface 310 of thesmoothing capacitor 211 by vacuum evaporation method or bonding method,so that the metal film on the smoothing capacitor 211 is soldered to theheat sink 230. Moreover, the smoothing capacitor 211 and the heat sink230 can be bolted together by bolts and nuts through an 0-ring. Beside,these bolts can be used as a bolt that fixes the heat sink 230 to themotor housing.

[0057] Although the front face 232′ of the heat sink 230 has a flatsurface, a concave can be formed on the front face 232′ of the heat sink230 so that the resin casing 311 of the smoothing capacitor 211 isinserted and fitted into the concave of the heat sink 230. This methodis used instead of the bonding between the smoothing capacitor 211 andthe heat sink 230.

[0058] (Fourth Embodiment)

[0059] A rotary electric machine according to a fourth embodiment has afollowing structure, as shown in FIGS. 8 and 9. In FIG. 9, the rotaryelectric machine includes a housing 401 having a cylindrical shape andan inverter module 402. A magnetic rotor type multi-phase synchronousmotor (not shown) is accommodated in the housing 401. Although notshown, the motor includes a stator core, a stator coil, a rotor, arotational shaft, and so on. The inverter module 402 has a base plate403, an insulating sheet 4, a power supply busbar 405, an output busbar406, a ground busbar 407, an insulated gate bipolar transistor (i.e.,IGBT) device 408 as a semiconductor switching device disposed on anupper arm, an IGBT device 409 disposed on a lower arm, and a cover 410.The housing 401 and the base plate 403 are formed by aluminum diecasting method, and the cover 410 is formed by press method of aluminumthin film. The base plate 403 is fixed to a rear plate 411 of thehousing 401 by a screw (not shown). The rear plate 411 is disposed on aninner circumference wall of the housing 401. A peripheral wall 412 ofthe housing 401 is protruded from the rear plate 411. The peripheralwall 412 is covered with the cover 410, which is made of resin. Thecover 410, the rear plate 411, and the peripheral wall 412 define anaccommodation space S. The inverter module 402 is accommodated in theaccommodation space S.

[0060] The base plate 403 has a coolant passage 431, which has a helicalpassage flowing a coolant. The base plate 403 contacts the peripheralwall 412. The power supply busbar 405 and the output busbar 406 arefixed on a rear face of the base plate 403 through an insulation sheet404. In this fixation, a well-known method is used. For example, each ofthe power supply busbar 405 and the output busbar 406 is coated with aninsulating resin except for an electric contact area in each of thepower supply busbar 405 and the output busbar 406, respectively. Then,each of the power supply busbar 405 and the output busbar 406 is fixedto the base plate 403 by a resin screw, respectively. Or the powersupply busbar 405 and the output busbar 406 are press-contacted on theinsulation sheet 404 by a holding plate of the base plate 403.

[0061] As shown in FIG. 9, a pillar 432 is protruded to the rear sidefrom a predetermined position of the base plate 403. The pillar 432connects and fixes to the ground busbar 407 at a top of the pillar 432.The power supply busbar 405 and the ground busbar 407 are disposedconcentrically with a rotational shaft of the motor, as shown in FIG. 8.The output busbar 406 has almost a rectangle shape, and is disposed onthe insulation sheet 404. The output busbar 406 is disposed between thepower supply busbar 405 and the ground busbar 407.

[0062] The IGBT devices 408, 409 disposed on the upper and lower arms,respectively, are composed of card type modules integrating an N-channelIGBT. The card type module includes a collector terminal, an emitterterminal, and a gate terminal. The collector terminal is connected to acollector electrode of the IGBT, which is disposed on the bottom surfaceof the IGBT. Each of the emitter terminal and the gate terminal isconnected to each of an emitter electrode and a gate electrode of theIGBT, respectively, which are disposed on upper surface of the IGBT.Side surface of the IGBT is covered with a resin mold. The gate terminalcan be disposed on the upper surface of the card type module and bearranged aside the emitter terminal. Moreover, the gate terminal can bedisposed on a side surface of the card type module. In FIG. 9, althoughthe IGBT devices 408, 409 corresponding to one phase of the multi-phaseinverter circuit are shown, the inverter module 402 has other four IGBTdevices corresponding to remaining two phases of the multi-phaseinverter circuit, as shown in FIG. 8.

[0063] In FIG. 8, a bottom terminal of the IGBT device 408 as acollector terminal is fixed on the power supply busbar 405 by a solderand the like. A bottom terminal of the IGBT device 409 is fixed on theoutput busbar 406 by a solder and the like. The output busbar 406includes a body 461 and a plurality of legs 462. The IGBT device 409 isfixed to the body 461 of the output busbar 406. The leg 462 of theoutput busbar 406 has a tongue-like shape and extends from the body 461to the outside of the base plate 403. The leg 462 stands at a peripheralend of the body 461 toward the cover 410, and is bent to the outside ofthe base plate 403. Then, the leg 462 is bent again toward the IGBTdevice 408, and is soldered to the emitter terminal of the IGBT device408.

[0064] The ground busbar 407 includes a ring body 471 and a plurality oflegs 472. The ring body 471 has a ring plate shape, and is mounted onthe pillar 432. The leg 472 extends from the ring body 471 to theoutside of the base plate 403, and is bent toward the IGBT device 409.Then, the leg 472 is soldered to the emitter terminal of the IGBT device409. Each gate terminal of the IGBT devices 408, 409 is connected to anexternal controller (not shown).

[0065] As shown in FIG. 8, the inverter circuit includes the IGBT device408 disposed on the upper arm, the IGBT device 409 disposed on the lowerarm, a pair of flywheel diodes 414, 415, and three-phase inverters U, V,W. The IGBT devices 408, 409 are connected in series. Each flywheeldiode 414, 415 is connected in parallel to each IGBT device 408, 409.The three-phase inverters U, V, W output different phase voltages. TheIGBT device 408 is connected as a collector follower, and the IGBTdevice 409 is connected as an emitter follower.

[0066] The three-phase inverters U, V, W are located in a perpendicularrelation to each other. Each three-phase lead 413U, 413V, 413W isprotruded from each phase of the stator coil into the accommodationspace S through the base plate 403 and the rear plate 411, respectively.Each three-phase lead 413U, 413V, 413W is adjacent to a sidecircumference wall of each body 461 of the output busbars 406,respectively. Each three-phase lead 413U, 413V, 413W are soldered toeach body 461 of the output busbars 406, respectively. The IGBT device409 on the lower arm and the flywheel diode 414 are connected to thebody 461 of the output busbars 406, and are adjacent each other in thecircumferential direction. The ring body 471 of the ground busbar 407and the upper electrode of the flywheel diode 414, i.e., the anodeelectrode of the flywheel diode 414, are connected to a leg 473 of theground busbar 407, which extends from the ring body 471 of the groundbusbar 407. Similarly, the IGBT device 408 on the upper arm and theflywheel diode 415 are connected to the power supply busbar 405, and areadjacent each other in the circumferential direction. The body 461 ofthe output busbar 406 and the upper electrode of the flywheel diode 415,i.e., the anode electrode of the flywheel diode 415, are connected to aleg 463 of the output busbar, which extends from the body 461 of theoutput busbar 406. The power supply busbar 405 having a ring plate shapefaces the base plate 403 in wide area through the insulation sheet 404.Here, the base plate 403 has the same electric potential as the groundbusbar 407, so that the smoothing capacitor 416 can be reduced in it'sdemanded capacity.

[0067] In the fourth embodiment, heat generated by the IGBT devices 408,409 conducts from the principal planes of the IGBT devices 408, 409 tothe base plate 403 through busbars, so that the IGBT devices 408, 409are cooled sufficiently. Moreover, the IGBT devices 408, 409 have nowire bonding for connecting, so that the output busbar 406 is downsized,a total wiring length is shortened, and the rotary electric machine isassembled easily. Further, the base plate 403 can be integrated with therear plate 411 of the housing 401, so that the housing 401 of the motoris strengthened. Then, the rear plate 411 can be thin, and the motor canbe cooled sufficiently through the rear plate 411. Further, each leg462, 472 is deformable so that deviation of size in other parts can beabsorbed by the deformation of the legs 462, 472.

[0068] Although the IGBT device is used as a semiconductor device, othersemiconductor switching devices can be used. For example, a bare chippower semiconductor device can be used. In this case, a plurality ofelectrode plates are formed on a pair of principal planes of the barechip power semiconductor device, and side surface of the bare chip powersemiconductor device is covered with a resin coating so that a card typepower semiconductor device is formed. Moreover, the power semiconductordevice can include, for example, an IGBT, a metal-oxide semiconductortransistor (i.e., MOS transistor), and a flywheel diode. In other words,the flywheel diode, the IGBT and/or the MOS transistor are integratedinto one card module. Further, the flywheel diode, the IGBT and/or theMOS transistor can be integrated into one semiconductor chip. As long asthe power semiconductor device is mounted on the busbar, any type ofpower semiconductor device can be used instead of the card type powersemiconductor device.

[0069] Further, the busbar is formed by lead frame method,alternatively, each busbar can be formed individually. For example, atfirst, a bare chip semiconductor device is bonded to a busbar, and thebusbar is fixed to a heat sink through an insulating sheet. Then, thebusbar is molded by resin. Moreover, a bare chip semiconductor device isbonded to a busbar, and is preliminary molded by resin so that the barechip semiconductor device is protected by the resin mold.

[0070] Further, a plurality of electrode plates are formed on a pair ofprincipal planes of a bare chip power semiconductor device, and sidesurface of the bare chip power semiconductor device is covered with aresin coating so that a card type power semiconductor device is formed.Busbars are fixed to two sides of the card type power semiconductordevice, respectively. Then, the busbars are fixed to the heat sinkthrough an insulating sheet.

[0071] Furthermore, the rear plate 411 of the motor and the invertermodule 402 can be integrated together so that the motor is downsized andlightened. Moreover, by the integration, each three-phase lead can beconnected in a beeline to each output busbar, respectively, so thatresistance of the output busbar and the three-phase lead are reduced.Moreover, cooling performance of each semiconductor device can besubstantially equalized.

[0072] (Modification of Fourth Embodiment)

[0073] The fourth embodiment is modified as follows. As shown in FIG.10, a smoothing capacitor 416 has an elliptic cylindrical shape, and isdisposed on the base plate 403. The smoothing capacitor 416 and thethree-phase inverter V are on the same diametric line, and the smoothingcapacitor 416 is also disposed from center to outside of the base plate403. The smoothing capacitor 416 has a positive terminal and a negativeterminal (not shown). The positive terminal is connected to the powersupply busbar 405 of the multi-phase inverter, and the negative terminalis connected to the ground busbar 407. A flat circumference wall of thesmoothing capacitor 416 is adhered to the ground busbar 407, so that thesmoothing capacitor 416 is cooled sufficiently by the coolant throughthe ground busbar 407. Then, the inverter module 402 can be formedcompactly.

[0074] The fourth embodiment is further modified as follows. As shown inFIG. 11, a base plate 430 has a plurality of steps, so that an outputbusbar 406 and a ground busbar 407 can be flat. An insulation sheet isnot shown in FIG. 11. The base plate 430 has a ground base 433, a secondbase 434 that is parallel to the ground base 433 and is higher than theground base 433 by a predetermined height, a third base 435 that is alsoparallel to the second base 434 and is higher than the second base 434by a predetermined height. An IGBT device 408 on an upper arm and aflywheel diode 415 (not shown) are disposed on the ground base 433through a power supply busbar 405. Similarly, an IGBT device 409 on alower arm and a flywheel diode 414 (not shown) are disposed on thesecond base 434 through a body 461 of an output busbar 406.

[0075] Even in this modification, the output busbar 406 has the body 461having a ring plate shape and a plurality of legs 462 that are protrudedfrom the body 461 to the outside of the base plate 430. The groundbusbar 407 has the body 471 having a ring plate shape and a plurality oflegs 472 that are protruded from the body 471 to the outside of the baseplate 430. Each leg 462, 472 is deformable so that deviation of size inother parts can be absorbed by the deformation of the legs 462, 472.Moreover, the legs 462, 472 have no bending portion in the axialdirection, so that manufacturing cost of the legs 462, 472 is reducedand a resistance of each leg 462, 472 is also reduced. Therefore, thecooling performance is promoted by the reduction of the resistance.

[0076] Such changes and modifications are to be understood as beingwithin the scope of the present invention as defined by the appendedclaims.

What is claimed is:
 1. A rotary electric machine, comprising: a statorcore, which has a cylindrical shape and includes a slot therein; arotor, which is rotatably supported inside of the stator core; a casing,which accommodates the rotor and the stator core; a stator coil, whichis inserted in the slot of the stator core, and includes a coil endprotruded from a side face of the stator core; a cooling unit, whichincludes a coolant passage; and an electric part, which is mounted onthe cooling unit, and controls the stator coil, Wherein the cooling unitis accommodated in spacing defined by a side face of the stator core andan outer circumference wall of the coil end, and contacts the side faceof the stator core.
 2. A rotary electric machine according to claim 1,wherein the coolant passage of the cooling unit is annular.
 3. A rotaryelectric machine according to claim 1, further comprising: a throughbolt for bolting the cooling unit and the stator core in an axialdirection of the rotor.
 4. A rotary electric machine according to claim2, wherein the cooling unit includes a plate and a body, the coolantpassage is disposed in the body and has an opening, the opening isopened in the axial direction of the rotor, and the plate has a ringplate shape and adheres to the body of the cooling unit so that theplate seals the opening of the coolant passage.
 5. A rotary electricmachine according to claim 4, further comprising: a through bolt forbolting the body and the plate of the cooling unit and the stator corein the axial direction of the rotor.
 6. A rotary electric machineaccording to claim 4, wherein the coolant passage has a helical passage,and the plate includes a coolant inlet and a coolant outlet that areconnected to two ends of the coolant passage, respectively.
 7. A rotaryelectric machine according to claim 1, wherein the body of the coolingunit includes a housing, the housing has a cylindrical shape, covers thestator core, and contacts an outer circumference wall of the statorcore.
 8. A rotary electric machine according to claim 4, wherein theelectric part is mounted on the plate of the cooling unit.
 9. A rotaryelectric machine according to claim 8, further comprising: a cover,which is mounted on the plate of the cooling unit so that the coverprotects the electric part.
 10. A rotary electric machine according toclaim 9, further comprising an electric terminal, wherein the electricterminal is mounted on the plate of the cooling unit, is protruded fromthe cover, and connects to an external power supply so that the externalpower supply supplies an electric power to the electric part through theelectric terminal.
 11. A rotary electric machine according to claim 1,wherein the rotor includes a centrifugal fan, which is disposed moreinside than the coil end in a radial direction of the rotor.
 12. Arotary electric machine according to claim 11, wherein the cooling unitincludes a cooling fin, which is protruded from the cooling unit so thata blow caused by the centrifugal fan is cooled with the cooling fin. 13.A rotary electric machine according to claim 4, further comprising abearing, wherein the rotor is rotatably supported with the plate of thecooling unit through the bearing.
 14. A rotary electric machineaccording to claim 1, wherein the electric part includes a semiconductorswitching device.
 15. A rotary electric machine according to claim 1,further comprising: a resin material, which is filled in spacing amongthe cooling unit, the stator core, and the coil end of the stator coil.16. A rotary electric machine according to claim 8, wherein the electricpart is mounted on one side of the plate of the cooling unit, and theother side of the plate faces the stator core.
 17. A rotary electricmachine according to claim 6, wherein an axial direction of the helicalpassage is parallel to the axial direction of the rotor.
 18. A rotaryelectric machine according to claim 1, wherein the electric part ismounted on one side of the cooling unit, and the stator core contactsthe other side of the cooling unit.
 19. A rotary electric machineaccording to claim 1, wherein the cooling unit is integrated with thecasing, the casing includes a ring-shape groove and a coolant pipe asthe cooling unit, and the coolant pipe is disposed in the ring-shapegroove.
 20. A rotary electric machine according to claim 1, wherein thestator core, the stator coil, and the rotor provide an alternatingcurrent dynamotor, and the electric part provides an inverter circuitfor controlling an electric power delivery between an direct currentpower supply and the alternating current dynamotor.
 21. A rotaryelectric machine according to claim 20, wherein the cooling unit hasfirst and second surfaces, the first surface of the cooling unit facesthe alternating current dynamotor, the second surface of the coolingunit is opposite to the first surface, the electric part includes asemiconductor switching device and a smoothing capacitor, thesemiconductor switching device is disposed between the direct currentpower supply and the stator coil, provides the inverter circuit forconverting direct current to alternating current or alternating currentto direct current, and is mounted on the second surface of the coolingunit so that the semiconductor switching device is cooled by the coolingunit, and the smoothing capacitor connects to a direct current terminalof the inverter circuit, and is mounted on the first surface of thecooling unit so that the smoothing capacitor is cooled by the coolingunit.
 22. A rotary electric machine, comprising: an alternating currentmotor with a stator coil; and an inverter, which is disposed on an axialside of the motor, and controls an electric power delivery between adirect current power supply and the stator coil of the motor, whereinthe inverter includes a semiconductor switching device, a smoothingcapacitor, and a cooling unit, the cooling unit has first and secondsurfaces, the first surface faces the motor, the second surface isopposite to the first surface, the semiconductor switching device isdisposed between the direct current power supply and the stator coil,provides an inverter circuit for converting direct current toalternating current or alternating current to direct current, and ismounted on the second surface of the cooling unit to be cooled by thecooling unit, and the smoothing capacitor connects to a direct currentterminal of the inverter circuit, and is mounted on the first surface ofthe cooling unit to be cooled by the cooling unit.
 23. A rotary electricmachine according to claim 22, further comprising: a conductive layer;and an insulating sheet, wherein the conductive layer is disposed on thesecond surface of the cooling unit so that the semiconductor switchingdevice is mounted on the conductive layer, and the insulating sheet isdisposed between the conductive layer and the second surface of thecooling unit.
 24. A rotary electric machine according to claim 23,wherein the conductive layer provides a higher potential electrode ofthe direct current power supply.
 25. A rotary electric machine accordingto claim 22, further comprising: a first conductive layer with aninsulating sheet, which is disposed on the second surface of the coolingunit; and a second conductive layer, which is disposed directly on thesecond surface of the cooling unit, wherein the semiconductor switchingdevice includes first and second semiconductor elements, the firstsemiconductor element is mounted on the first conductive layer, theinsulating sheet is disposed between the first conductive layer and thesecond surface of the cooling unit, and the second semiconductor elementis mounted on the second conductive layer.
 26. A rotary electric machineaccording to claim 25, wherein the second conductive layer provides analternating current line of the inverter circuit for connecting to thestator coil.
 27. A rotary electric machine according to claim 22,wherein the inverter includes a microcomputer, which outputs informationabout the inverter circuit to an external system.
 28. A rotary electricmachine according to claim 22, wherein the cooling unit includes acoolant passage having an opening on the first surface of the coolingunit, and the smoothing capacitor is fixed to the first surface of thecooling unit so that the opening of the coolant passage is sealed by thesmoothing capacitor.
 29. A rotary electric machine, comprising: acooling unit having first and second surfaces, which are parallel toeach other; a capacitor mounted on the first surface of the coolingunit; and an electric part mounted on the second surface of the coolingunit, wherein the cooling unit includes a coolant passage with anopening on the first surface of the cooling unit, and the capacitor isfixed to the first surface of the cooling unit so that the opening ofthe coolant passage is sealed by the capacitor.
 30. A rotary electricmachine according to claim 28, wherein the cooling unit has a concave,and the concave is disposed on the first surface of the cooling unit sothat the smoothing capacitor is inserted and fitted into the concave ofthe cooling unit and the opening of the cooling passage is sealed by thesmoothing capacitor.
 31. A rotary electric machine according to claim25, wherein the first and second conductive layers are made of copper.32. A rotary electric machine according to claim 22, wherein each of thesmoothing capacitor and the semiconductor switching device has a resincasing, respectively.
 33. A rotary electric machine, comprising: acooling unit having a surface; an insulation sheet; a first busbarmounted on the surface of the cooling unit through the insulation sheet;a first electric part mounted on the first busbar; a second busbar,which includes a body mounted on the surface of the cooling unit throughthe insulation sheet and a leg protruded from the body; a secondelectric part mounted on the body of the second busbar; and a thirdbusbar mounted on the surface of the cooling unit, wherein the leg ofthe second busbar has a bottom face connected to a top face of the firstelectric part, the second busbar has a predetermined step between thebody and the leg of the second busbar, and the third busbar has a bottomface connected to a top face of the second electric part.
 34. A rotaryelectric machine, comprising: a cooling unit having a surface; aninsulation sheet; a first busbar mounted on the surface of the coolingunit through the insulation sheet; a first electric part mounted on thefirst busbar; a second busbar, which includes a body mounted on thesurface of the cooling unit through the insulation sheet and a legprotruded from the body; a second electric part mounted on the body ofthe second busbar; and a third busbar mounted on the surface of thecooling unit, wherein the leg of the second busbar has a bottom faceconnected to a top face of the first electric part, the third busbar isconnected to a top face of the second electric part, and the surface ofthe cooling unit has a predetermined step so that the body and the legof the second busbar are flat.
 35. A rotary electric machine accordingto claim 33, wherein the top face of the first electric part provides analternating current output electrode and a bottom face of the firstelectric part provides a higher potential direct current electrode, andthe top face of the second electric part provides a lower potentialdirect current electrode and a bottom face of the second electric partprovides an alternating current output electrode.
 36. A rotary electricmachine according to claim 35, wherein the second electric part includesa control electrode, the control electrode is mounted on the top face ofthe second electric part and is adjacent to the lower potential directcurrent electrode.
 37. A rotary electric machine according to claim 33,wherein the third busbar includes a body mounted on the surface of thecooling unit and a leg protruded from the body, the leg of the thirdbusbar has a bottom face connected to a top face of the second electricpart, and the third busbar has a predetermined step between the body andthe leg of the third busbar.
 38. A rotary electric machine according toclaim 33, further comprising a motor, wherein the motor has a rotationalshaft, the cooling unit is mounted on the motor, the first busbar has aring plate shape concentric with the rotational shaft of the motor, andthe first and second electric parts are aligned in a radial direction ofthe rotational shaft and are adjacent each other.
 39. A rotary electricmachine according to claim 38, wherein a plurality of pairs of the firstand second electric parts provide a multi-phase inverter circuit, andeach pair of the first and second electric parts has a rotationalsymmetry around the rotational shaft of the motor.
 40. A rotary electricmachine according to claim 38, further comprising: a smoothing capacitormounted on the surface of the cooling unit, wherein the smoothingcapacitor has a pair of terminal for connecting the first and thirdbusbars, respectively, three pairs of the first and second electricparts provide a three-phase inverter circuit, the smoothing capacitorand one pair of the first and second electric parts are disposed on afirst diametric line of the motor, and the other two pairs of the firstand second electric parts are disposed on a second diametric line of themotor so that the second diametric line is perpendicular to the firstdiametric line.
 41. A rotary electric machine according to claim 38,wherein the leg of the second busbar extends from the body of the secondbusbar to an outside of the radial direction of the rotational shaft ofthe motor, and has a tongue-like shape.
 42. A rotary electric machineaccording to claim 38, wherein the third busbar includes a body having aring plate shape concentric with the rotational shaft of the motor and aleg protruded from the body of the third busbar, and the leg of thethird busbar has a bottom face connected to a top face of the secondelectric part.
 43. A rotary electric machine according to claim 38,wherein the cooling unit is integrated with the motor.
 44. A rotaryelectric machine according to claim 39, further comprising: a smoothingcapacitor mounted on the surface of the cooling unit, wherein thesmoothing capacitor having a pair of terminal for connecting the firstand third busbars, respectively, a plurality of pairs of the first andsecond electric parts provides a multi-phase inverter circuit, theplurality of pairs of the first and second electric parts and thesmoothing capacitor are disposed in rotational symmetry around therotational shaft of the motor.
 45. A rotary electric machine accordingto claim 33, wherein the first and second electric parts include aflywheel diode and an insulated gate bipolar transistor, respectively.46. A rotary electric machine according to claim 33, wherein the firstand second electric parts include a flywheel diode and a metal-oxidesemiconductor transistor, respectively.
 47. A rotary electric machineaccording to claim 33, wherein the first and second electric partsprovide card type power semiconductor modules, respectively.
 48. Arotary electric machine according to claim 36, wherein the firstelectric part forms a collector follower, and the second electric partforms an emitter follower.
 49. A rotary electric machine, comprising: acooling unit having a surface for mounting parts; an insulation sheet; afirst busbar mounted on the surface of the cooling unit through theinsulation sheet; a first electric part mounted on the first busbar; asecond busbar, which includes a body mounted on the surface of thecooling unit through the insulation sheet and a leg protruded from thebody; a second electric part mounted on the body of the second busbar;and a third busbar , which includes a body mounted on the surface of thecooling unit and a leg protruded from the body, wherein the leg of thesecond busbar has a bottom face connected to a top face of the firstelectric part, the leg of the third busbar has a bottom face connectedto a top face of the second electric part, and the surface of thecooling unit has first and second predetermined steps so that each bodyand leg of the second and third busbars is flat, respectively.
 50. Arotary electric machine according to claim 49, further comprising amotor, wherein the motor includes a rotational shaft, the cooling unitis mounted on the motor, the first busbar has a ring plate shapeconcentric with the rotational shaft of the motor, the body of the thirdbusbar has a ring plate shape concentric with the rotational shaft ofthe motor, and the first and second electric parts are aligned in aradial direction of the rotational shaft and are adjacent each other.